package com.interview.javabasic.DataStructrue;/*
@李子宁
Happy,happy everyday!
冲鸭！
*/

import java.util.Scanner;

public class CircleArrayQueueDemo {
    public static void main(String[] args) {
        //测试数组模拟环形队列
        //测试,队列的有效数据最大是三
        CircleArray arrayQueue = new CircleArray(4);
        char key = ' ';
        Scanner scanner = new Scanner(System.in);
        boolean loop = true;
        //输出一个菜单
        while (loop){
            System.out.println("s(show)：显示队列");
            System.out.println("e(exit)：退出程序");
            System.out.println("a(add)：添加数据到队列");
            System.out.println("g(get)：从队列取出元素");
            System.out.println("h(head)：查看队头元素");
            key = scanner.next().charAt(0);
            switch (key){
                case 's':
                    arrayQueue.showQueue();
                    break;
                case 'a':
                    System.out.println("请输入一个数：");
                    int value = scanner.nextInt();
                    arrayQueue.addQueue(value);
                    break;
                case 'g':
                    try {
                        int res = arrayQueue.getQueue();
                        System.out.printf("取出的数据是%d\n",res);
                    }catch (Exception e){
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'h':
                    try {
                        int res = arrayQueue.headQueue();
                        System.out.printf("队列头的数据是%d\n",res);
                    }catch (Exception e){
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'e':
                    scanner.close();
                    loop=false;
                    break;
                default:
                    break;
            }
        }
        System.out.println("程序退出");

    }
}
class CircleArray{
    private int maxSize;//最大容量
    private int front;
    private int rear;
    private int[] arr;//数组用于存放数据
    public CircleArray(int arrMaxSize){
        maxSize = arrMaxSize;
        arr = new int[maxSize];
    }

    //判断是否满：
    public boolean isFull(){
        return (rear+1)%maxSize==front;
    }

    //判断队列是否为空
    public boolean isEmpty(){
        return rear==front;
    }

    //添加数据到队列
    public void addQueue(int n){
        if (isFull()){
            System.out.println("队列满，不能加入数据");
            return;
        }
        arr[rear] = n;
        //将rear后移，这里需要考虑取模
        rear = (rear+1)%maxSize;
    }

    //数据出队列
    public int getQueue(){
        //判断队列是否空
        if (isEmpty()){
            //抛出异常
            throw new RuntimeException("队列为空，不能取数据！");
        }
        //这里需要分析出front是指向队列的第一个元素
        //1、先把front对应的值保存到一个临时变量中
        //2、将front后移,考虑取模
        //3、返回临时变量
        int val = arr[front];
        front = (front+1)%maxSize;
        return val;
    }

    //显示队列的所有数据
    public void showQueue(){
        //遍历
        if (isFull()){
            System.out.println("队列为空。");
            return;
        }
        //从front开始遍历，遍历多少个元素
        for (int i = front; i < front+size(); i++) {
            System.out.printf("arr[%d]=%d\n",i%maxSize,arr[i%maxSize]);
        }
    }

    //求出当前队列的有效数据个数
    public int size(){
        return (rear + maxSize - front)%maxSize;
    }

    //显示队列的头部，注意：不是取出数据
    public int headQueue(){
        //判断
        if (isEmpty()){
            throw new RuntimeException("队列为空");
        }
        return arr[front];
    }

}
